1. Field of the Invention
The present invention relates to orthopedic devices for protecting the human knee, and it relates more particularly to an orthopedic device adapted to protect the knee against injury from lateral forces and impacts which may occur during sports activities.
2. Description of the Prior Art
There is widespread need for knee protection apparatus capable of absorbing forces or impacts directed toward the lateral side of the knee and redistributing such forces or impacts along the leg so as to protect a previously injured knee from further injury. A typical circumstance where such knee protection equipment would be desirable is during a game of football, where for example the person with a previously injured leg has that leg planted and another player puts a shoulder pad into the lateral side of the leg.
Applicants are aware of only two prior art protective devices directed to this specific problem, and neither of these devices has proven sufficiently satisfactory to come into widespread use. These two prior art devices are made in accordance with disclosures in U.S. Pat. No. 4,249,524 to Anderson and U.S. Pat. No. 3,528,412 to McDavid. The Anderson device consists of arms adapted to be attached to the lateral side of the thigh and calf, respectively, either by tape or neoprene wrap held with Velcro. The proximal or near ends of the arms (relative to the knee) are pivotally connected to opposite ends of a rigid metal bridge, the purpose of the device being to receive lateral forces at the bridge instead of such forces being applied directly to the knee, and to distribute such lateral forces to the femur and tibia. The Anderson device is intended to be used by football players, but it has problems such that football players in fast running positions, such as running backs, ends and the like, will not wear it. One problem is that the Anderson device has single-overlap pivots which must be fairly tight for stability, resulting in too much friction during running and hence impairment of full running freedom. Another problem with the Anderson device is that lateral force against the bridge tends to be applied to the leg primarily directly under the regions of the pivots, which is still fairly well localized at regions close to the knee, and not distributed well along the lengths of the arms to which the bridge is pivoted. A further problem with the Anderson device is that although it is biaxially pivotal, the movements at the two pivots are completely independent of each other, so that just one or just the other of the pivotal connections may move, which may cause slippage. Also, the pivots are too far apart to simulate the hinging action of the human knee.
The device of the McDavid patent is essentially the same as the Anderson device except it has only a single single-overlap pivot located generally proximate the knee. The McDavid device has the same two principal problems as the Anderson device, namely, the single-overlap pivot needs to be fairly tight for stability, resulting in an undesirably large amount of friction during running, and lateral forces against the raised pivot tend to be applied to the leg at localized regions close to the knee and not distributed well along the lengths of the pivoted arms strapped to the thigh and calf.
A further problem with both the Anderson and McDavid prior art athletic knee protective devices is that they cause lateral forces and impacts to be applied so close to the knee as to be applied substantially directly to bone, namely to the femur and fibia proximal the knee. This causes further localization of force and impact application, with the further likelihood of trauma directly to the femur and the immediate covering tissues.
Applicants are aware of a number of other prior patents directed to knee braces for protecting or supporting or limiting the motion of injured knees, but are not aware of any devices other than the Anderson and McDavid devices manufactured for the purpose of protecting the knee from lateral forces or impacts. Two of these other patents, Erichsen U.S. Pat. No. 4,381,768 and Lerman U.S. Pat. No. 4,372,298 are relevant to the present invention because of biaxial, geared hinge structures similar to the geared hinge structure employed in applicants' invention. Stops are provided on the Lerman gears to limit the travel in both directions. However, neither the Erichsen or Lerman devices would be usable to absorb and redistribute lateral forces or impacts. Thus, in both of these patents, the hinged arms are described as being rigid. In Erichsen, the hinge appears to be right against the side of the knee so that lateral forces or impacts would be directly transmitted to the knee, and in Lerman, pads are attached to the hinges of opposite sides of the knee, so that lateral forces or impacts against the hinge on the lateral side of the knee would be transmitted through the respective pad directly to the knee.
Cummins U.S. Pat. No. 4,245,629 states that one of the purposes of the disclosed device is for absorbing and spreading an external blow, and Cummins is also of interest because it discloses a biaxial-type hinge structure, although it is not geared. This is a double overlap-type hinge with three tongues, described as being rigid, extending from each side of the hinge and independently pivoted in the hinge. The Cummins device does not appear to space the hinge structure from the knee, and it appears that lateral forces or impacts against the hinge would be applied directly to the knee joint or through the rigid tongues to localized regions of the leg very close to the knee.
McClure, Jr. U.S. Pat. No. 3,350,719 discloses substantially flat upper and lower brace bars that appear to be rigid, connected at a biaxial hinge. Lateral forces or impacts would either be applied through the hinge directly to the knee or through the brace bars to localized regions close to the knee.
Peckham U.S. Pat. No. 3,194,233 discloses lateral and medial leaf-type springs whch bow outwardly. There is no means disclosed in this Peckham patent for spreading force to the femur awd tibia at substantial spacings from the knee, and sponge pads are compressed against opposite sides of the knee joint by knee-encircling members which would cause impacts to be transmitted directly proximate the knee joint. Another Peckham U.S. Pat. No. 2,467,907 also discloses bowed springs, but so arranged that impacts would be applied directly to the knee joint. Schulman U.S. Pat. No. 3,074,400 also discloses springs in a kneecap brace, but these are not hingedly connected. Patents such as Whitehead U.S. Pat. No. 3,898,697 and Buring 4,409,689 are exemplary of a number of patents which disclose shell-like forms fitting over portions of the upper and lower leg adjacent to the knee.
Another problem which particularly adversely affects the performance of the prior art athletic knee protective devices disclosed in the Anderson U.S. Pat. No. 4,249,524 and the McDavid U.S. Pat. No. 3,528,412, and which also adversely affects the performance of other knee braces in general, is that such devices tend to preload the knee with an unnatural force couple which predisposes the knee to injury. Such preloading is compounded in athletic knee protective devices such as those of Anderson and McDavid by variations in the preloading which occur during athletic movements, and also by the intensification of lateral forces and impacts to the protective devices.
This preloading phenomenon occurs in the following way. The knee braces have a thigh bar which is hingedly connected to a shin bar by hinge means which is pivotal in the anterior/posterior direction, but which is substantially rigid in the lateral/medial direction. The thigh and shin bars are either directly strapped or taped to the thigh and shin, respectively, as with the Anderson ad McDavid devices, or are attached to the thigh and shin through some sort of cuff or pad devices which are in turn strapped or taped to the thigh and shin. There are wide variations in the longitudinal contours of the outer or lateral side of the human leg, and as a general rule, the brace bars, cuffs or the like do not accurately align with the external lateral contours of the legs to which they are applied, and when the attachment is secured by strapping or taping, then this misalignment will result in a lateral/medial type of preloading at the knee. The relative geometry between the contours of the thigh and shin will vary for various angles of flexion of the knee, and for varying conditions of muscle flexure of the thigh and shin muscles, so that this preloading will vary during activity of the wearer, and of course this becomes most intense for the heavy athletic endeavors for which athletic knee protectors such as the Anderson and McDavid protectors are designed. With regard to the Anderson and McDavid prior art athletic knee protective devices, this problem is further compounded by two factors. The first is that the single overlap-type pivots employed in the Anderson and McDavid devices are, as aforesaid, required to be fairly tight for stability, which means that there is little or no lateral give at the pivots to compensate for the preloading. The second factor is that the Anderson and McDavid devices are intended to protect the knee against lateral forces and impacts, and with the knee in a preloaded condition, such lateral forces and impacts are more likely to cause injury to the knee than if the knee were not preloaded.
Prior to the present invention, the only known means for reducing the adverse effects of preloading was the use of braces custom-made to fit the lateral contours of invdividual legs. However, this was tedious and expensive, and did not accommodate the variations in leg contour associated with movement.
Another problem which is, again, most serious with respect to knee braces specifically intended for protection against lateral forces and impacts such as the Anderson and McDavid braces, but which is also a problem with other knee braces in general, is that the anterior/posterior contours of the braces where they are attached to the thigh and shin do not, in general, match the corresponding anterior/posterior curvatures of the thighs and shins of the wearers. This tends to concentrate the attachment and operational loads of the braces at localized regions of the thigh and shin, which can cause discomfort to the wearer and instability of the brace in operation. This problem is most severe in knee protective devices such as those of Anderson and McDavid where the rigid brace bars themselves are directly strapped or taped to the thigh and shin, and where they are intended to transmit lateral forces and impacts to the thigh and shin.